Acquisitions - Pro Forma Information (Details) - Alpha $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2021 USD ($) $ / shares
Business Acquisition [Line Items]
Net sales | $	$ 3,250,332
Net earnings attributable to EnerSys stockholders | $	$ 181,915
Net earnings per share attributable to EnerSys stockholders - basic (in dollars per share) | $ / shares	$ 4.19
Net earnings per share attributable to EnerSys stockholders - assuming dilution (in dollars per share) | $ / shares	$ 4.12